Maybe those were the quarters for the crewmembers from low and zero gravity planets.
I could imagine they might have portals that are like the windows on glass bottom boats. You can't walk on them, but they'd have a railing that you could stand around and look down and out of the ship.
Voyager had an episode once that partly revolved around one crewmember that worked in the bowels of the ship. He was a real low-abition type guy that prefered to stay with his current duties because he had a nice view. It was one of those down facing windows. It wasn't really on the floor though. It was kind of at a steep down angle at the base of the wall where you could look out it as you walked by.